Linking habitat selection to brood success in greater sage-grouse

Examining links between the fitness of individual organisms and their habitat-based decisions is useful to identify key resources for conservation and management of a species, especially at multiple spatial scales because selection of habitat attributes may vary with spatial scale. Decisions of habitat use by brood-rearing Greater Sage-Grouse (Centrocercus urophasianus) may influence the survival of chicks. We conducted radiotelemetry on 38 sage grouse broods within Mono County, California, during 2003–2005. At relocation and random sites, we measured habitat characteristics at three spatial scales using field procedures (scale, 0.03 ha) and Geographical Information System tools (scales, 7.9 ha and 226.8 ha). We then conducted three data analyses using an information-theoretic modeling approach. The purpose of these analyses was to: (1) identify habitat factors that were selected (defined as use disproportionate to availability) by sage grouse broods; (2) identify habitat factors associated with brood success (defined as 1 live chick at 50 days post-hatch; 24 were successful, 14 unsuccessful); and (3) evaluate brood success as a function of habitat selection indices for brood-rearing sage grouse. At the smallest spatial scale (0.03 ha), grouse with broods selected areas with greater perennial forbs and higher richness of plant species. At larger scales (7.9 ha and 226.8 ha), areas with Utah juniper (Juniperus osteosperma) and singleleaf pinyon pine (Pinus monophylla) encroachment were avoided by grouse. Most importantly, the probability of fledging a brood increased as sage grouse females selected habitats with greater densities of perennial forbs (0.03 ha) and higher meadow edge (perimeter to edge ratio; 7.9 ha), perhaps because these areas provided a balance of food and protective cover for chicks. These results suggest that managers should discourage tree encroachment and preserve and enhance sagebrush stands interspersed with perennial forbs and a mixture of small upland meadows.